In recent years, automobile driving population has greatly increased. The speedway progress of technology enabled the automobile companies to thrive. People become to think highly of the improvement of automobile performance as well as the source of energy. Since there is a high demand for clean energy, electric vehicles (EV) gain access to markets. Thereafter, electric vehicles have become popular due to social development and national policy promotion.
Various kinds of electric vehicles have been produced, after the creation of electronic vehicle systems, which utilize new intelligence techniques, providing user customization of traffic control environment system, such as driving environments, traffic conditions, intelligent driving and also charging system. For example, new types of electric automobiles are all equipped with Vehicle Control Unit (VCU), also known as Vehicle Control System or Vehicle Integrated Unit. Vehicle Control Unit enables the users to give commands under different control circumstances, featured in safety protection function and complete controlled area network (CAN) interface for signals integration among systems. Automobile application system has become indispensable that not only elevates road safety, but also makes electric vehicles become a trend.
Current voltage of power supply for VCU of electric vehicles is recognized as Accessory Power Supply (APS), generally divided into two power-supplies, 12V and 24V. Small-sized automobiles apply 12V, such as passenger vehicles and trucks. Large-sized automobiles apply 24V, such as large motor vehicles, large trucks or buses. Thus, both standards of direct-current (DC) motors of power supplies should be equipped at charging station with VCU.
When charging automobiles of 24V APS with 12V power supply, the operating voltage of 12V cannot meet the demands of 24V APS of VCU which results in malfunctioning of instrument panel, battery management system (BMS) or insulation tester during power supply and vice versa. The power supply machines should be manufactured respectively for 12V and 24V auxiliary power of automobiles. Even it is modified to make 12V and 24V power supply wires compatible, the complexity of circuits will accelerate the depletion of circuit components.
Moreover, drivers or users of electric vehicles tend to be unknown or forgetful about their EVs' voltage power supply for VCU and also confused about power supply process of VCU. As a result, even though they arrive at charging station, they make it difficult to decide the charging voltage for VCU. If the VCU will be provided in a variety, the charging system of electric vehicles will bring forth more problems in that it is much more difficult for the users to decide and memorize the suitable voltage power supply.